Hi All,
Agree with Eric and Jim. We'd like to see either a spectrum or a
list of moments 0-3+, preferably directional, but just magnitude would
be nice.
We are trying to get at a Stokes drift climatology for the forcing
of near-surface wave-drivent turbulence in climate models.
Directional 3rd moment would be a nice direct measure of surface
Stokes drift. However, the whole spectrum is needed for direct
subsurface info. Jim is right that breaking is much harder. But, if
there commonly were spectra, even 1d for data lacking directional
sensors, this would be fantastic!
Furthermore, from a cf point of view, putting it out there that we
care about things other than significant wave height might stimulate
modelers and data to release these other variables.
We have found that the wave models do a great job on variables they
assimilate globally (e.g., significant wave height from altimeters).
They do an OK job with variables they assimilate sparsely (e.g., buoy
mean wave period). This is true even when the same models are run
*not assimilating data*. That is, if there's data to compare to then
the model algorithms and parameterizations improve to get it right.
Models do a significantly poorer job of getting the spectral shapes
right, since there is little ot no systematic data to constrain them
or train them against. So, if cf gives out a spectral format, then
some sites will keep them. Even if it's nondirectional, it can still
be used to constrain and train models.
Cheers,
-Baylor
On Wed, Oct 27, 2010 at 12:22 AM, Jim Thomson
<jthomson at apl.washington.edu> wrote:
>
> Agreed with Eric, completely. ?The big difficulty is that many sites do not have instruments capable of resolving directional spectra... some of these sites even the scalar spectra are not very good. ?The high-frequency tail is thought to be important for many of the quantities you list, so posting full spectra is probably the best approach.
>
> For example, bulk steepness (amplitude x wavenumber at the peak) is often less important for wave breaking than "wave saturation" (spectral steepness given by the 5th moment) at frequencies up to several multiples above the peak. ?Still, this is not sufficient to prescribe breaking (else I would retire and go surfing). ?Estimating these higher-order/dynamic quantities may be beyond the scope of the OS database, but at least if full spectra were available, users could make their own estimates. ?This has been working well for CDIP.
>
> -Jim
>
> On Oct 26, 2010, at 10:24 PM, Eric D'Asaro wrote:
>
>> Meghan et. al:
>>
>> I think we would be missing a great opportunity if we used only the wave variables proposed below. ?We have good dynamical reasons to think that waves are important in upper ocean dynamics and not just for purposes of directing shipping or filling up mandated data bases. I expect that in the future, ocean models will be coupled to wave models (as is already done for tropical cyclone models) and that historical wave data will be important in developing and verifying these models. ? In another project we are struggling with trying to reconstruct dynamically appropriate wave spectra from historical wave data that is archived in such a way as to make proper reconstruction very difficult. ?It would be a great waste if OceanSITES makes the same mistake.
>>
>> Variables should be added to the list that are sufficient to
>> 1. Resconstruct the important features of the directional wave spectrum, including energy and momentum flux and their depth profiles
>> 2. Provide indications of the wave steepness and breaking probabilities.
>>
>> Specific suggestions are perhaps better made by others (Baylor?, Jim? Ramsey?).
>>
>>
>>>>
>>>> -------- Original Message --------
>>>> Subject: ? ?Fwd: Seeking new CF standard names (waves and biogeochem)
>>>> Date: ? ? ? Thu, 21 Oct 2010 10:37:36 -0400
>>>> From: ? ? ? Nan Galbraith <ngalbraith at whoi.edu>
>>>> Reply-To: ? ngalbraith at whoi.edu
>>>> To: ots-dmt <oceansites-dmt at jcommops.org>
>>>>
>>>> Hi all -
>>>>
>>>> For anyone in OceanSITES who measures waves, there's a recent
>>>> discussion on the CF mailing list about new standard names. This
>>>> would be a good time to weigh in, if you haven't already, since we'll
>>>> want to use these terms in OceanSITES data files if and when we
>>>> include wave parameters.
>>>>
>>>> You need to be a member of the CF list to post a reply. You can join
>>>> at
>>>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>>>> .
>>>>
>>>> There's also been some discussion on biogeochem terms that might
>>>> be useful to some here.
>>>>
>>>> Regards -
>>>> Nan
>>>>
>>>> -------- Original Message --------
>>>> Subject: ? ?Re: [CF-metadata] Seeking new CF standard names (9) for sea
>>>> surface wave parameters
>>>> Date: ? ? ? Thu, 21 Oct 2010 11:09:29 +1100
>>>> From: ? ? ? andrew walsh
>>>> <awalsh at metoc.gov.au>
>>>>
>>>>
>>>>
>>>>
>>>> Hi Jonathon and CF metadata list,
>>>>
>>>> Summarising our discussions thus far we propose:
>>>>
>>>> 2 new Cell methods:
>>>>
>>>> root_mean_square
>>>> mean_of_upper_decile
>>>>
>>>> and these new standard names:
>>>>
>>>> sea_surface_wave_height (common concept)
>>>> sea_surface_wave_mean_crest_period
>>>> sea_surface_wave_significant_wave_period
>>>> sea_surface_wave_period_at_second_largest_peak_of_variance_spectral_density
>>>> sea_surface_wave_variance_spectral_density_zeroth_frequency_moment
>>>> sea_surface_wave_root_mean_square_amplitude_from_variance_spectral_density
>>>>
>>>> The sea_surface_wave_height is a common concept (standard name) which may be
>>>> qualified by a cell_method attribute to realise the actual variable. The
>>>> sea_surface_wave_height
>>>> when combined with a cell method of:
>>>>
>>>> time: mean
>>>> time: maximum
>>>> time: root_mean_square
>>>> time: mean_of_upper_decile
>>>>
>>>> will describe the statistical wave height variables:
>>>>
>>>> sea_surface_mean_wave_height
>>>> sea_surface_maximum_wave_height
>>>> sea_surface_root_mean_square_wave_height
>>>> sea_surface_wave_mean_of_highest_one_tenth_waves
>>>>
>>>> respectively.
>>>>
>>>> I have attached a spreadsheet which contains the names, descriptions and units
>>>> of the variables proposed.
>>>>
>>>> Looking forward to getting final approval to add these to the CF name lists.
>>>>
>>>>
>>>> Andrew Walsh
>>>> Data Facilitator AODN
>>>>
>>>> ----- Original Message -----
>>>> From: "Jonathan Gregory"
>>>> <j.m.gregory at reading.ac.uk>
>>>>
>>>> To: "andrew walsh"
>>>> <awalsh at metoc.gov.au>
>>>>
>>>> Cc:
>>>> <cf-metadata at cgd.ucar.edu>; "Mark Kulmar"<Mark.Kulmar at mhl.nsw.gov.au>
>>>>
>>>> Sent: Wednesday, October 13, 2010 20:21
>>>> Subject: [CF-metadata] Seeking new CF standard names (9) for sea surface wave
>>>> parameters
>>>>
>>>>
>>>>> Dear Andrew
>>>>>
>>>>>> Yes, but depends on the community (list) accepting the idea of having a
>>>>>
>>>>> Good. I think we are agreed then to propose these new cell methods:
>>>>>
>>>>> root_mean_square
>>>>> mean_of_upper_decile
>>>>>
>>>>> and these new standard names:
>>>>>
>>>>> sea_surface_wave_height
>>>>> sea_surface_wave_mean_crest_period
>>>>> sea_surface_wave_significant_wave_period
>>>>> sea_surface_wave_period_at_second_largest_peak_of_variance_spectral_density
>>>>> sea_surface_wave_variance_spectral_density_zeroth_frequency_moment
>>>>> sea_surface_wave_root_mean_square_amplitude_from_variance_spectral_density
>>>>>
>>>>> I agree that the last will avoid confusion with the RMS of wave height.
>>>>>
>>>>> I agree also that this depends on users being comfortable with the concepts
>>>>> being split into two attributes, in accordance with the usual CF practice,
>>>>> but deciding on how to join them up as common_concepts will help. Comments
>>>>> from others would help. It is good that Roy supports this compromise.
>>>>>
>>>>> Best wishes
>>>>>
>>>>> Jonathan
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>>
>>>> ? ? ? ? ? ? ? ? ? ? ? ? ?Cliquez sur l'url suivante
>>>>
>>>> https://www.mailcontrol.com/sr/tjkP04wPWEHTndxI!oX7UpBlscM9Pl1fAM1p1zO6h070olZRfJ6KoHxitOmXf8!eLCPtl9EVgldLRkMuvIdUTQ==
>>>>
>>>> ? ? ? ? ? ? ? ? ? si ce message est ind?sirable (pourriel).
>>>>
>>>>
>>>> <Proposed_wave_parm_names_for_CFlist.xls><Attached Message Part.txt>
>>>
>>>
>
>
--
? -Baylor
Received on Wed Oct 27 2010 - 22:01:17 BST
